After the virus, one can perhaps try Nerve Growth Factor, Stem Cells and Scar Tissue Removal, Anti Aging and Multiple Sclerosis Help Ver 2.0 (induces myelination and removes scar tissue), in addition to Brain Regeneration and BDNF.
Damage to (or dysregulation in) the olfactory sensory neurons and their receptors, and olfactory epithelium tissue.
(in addition to various other contributing factors)
It is considered a differential symptom, used in the diagnosis of this virus.
Some dysregulation of smell does occur in influenza at times, however at lower rates and severity, with differences in potential mechanisms, associated issues and longer term experiences.
Whilst zinc is certainly required for enzymes involved in processing smell or taste and one factor, it is not the only factor involved.
There is typically some damage to the nervous system from this virus due to downstream effects from disruption of the blood brain barrier and endothelial cell junctions.
(Injury to the nervous system is not primarily due to difficulty breathing as such—disruption of endothelial cell junctions and the blood brain barrier by itself can cause significant hypoxia in the brain in absence of this.)
Rather than preceding it, hypoxia in the lungs and body can be secondary to disruption of blood tissue barriers, and inflammation and hypoxia in the brain.
It can be difficult to notice or self-diagnose all impacts on the nervous system, depending upon whether any acute symptoms are noticeable.
Influenza does not disrupt the blood brain barrier and nervous system in the same manner.
(although there may be similarities shared, depending upon the specifics in any particular situation)